Eitr

Eitr is a mythical substance in Norse mythology. This liquid substance is the origin of all living things: the first giant Ymir was conceived from eitr. The substance is supposed to be very poisonous and is also produced by Jörmungandr (the Midgard serpent) and other serpents.

The last line of the stanza in Vafþrúðnismál where Vafþrúðnir says "that is why we are easily angered", is a word-play with the meaning of the word eitr, as it also means anger/angry (similar to "poison a relationship").[1]